The function set_menu_opts sets all the given menu's
option bits (menu option bits may be logically-OR'ed
together).
The function menu_opts_on turns on the given option bits,
and leaves others alone.
The function menu_opts_off turns off the given option
bits, and leaves others alone.
The function menu_opts returns the menu's current option
bits.
The following options are defined (all are on by default):
O_ONEVALUE
Only one item can be selected for this menu.
O_SHOWDESC
Display the item descriptions when the menu is
posted.
O_ROWMAJOR
Display the menu in row-major order.
O_IGNORECASE
Ignore the case when pattern-matching.
O_SHOWMATCH
Move the cursor to within the item name while pat-
tern-matching.
O_NONCYCLIC
Don't wrap around next-item and previous-item,
requests to the other end of the menu.